use crate::http::context::{AppContext, OpenApiResult, bad_request};
use crate::io::story_metadata::{StoryMetadata, parse_front_matter};
use crate::workflow::{
    StoryTestResults, TestCaseResult, TestStatus, evaluate_acceptance, summarize_results,
};
use poem_openapi::{Object, OpenApi, Tags, payload::Json};
use serde::Deserialize;
use std::collections::BTreeSet;
use std::fs;
use std::sync::Arc;

#[derive(Tags)]
enum WorkflowTags {
    Workflow,
}

#[derive(Deserialize, Object)]
struct TestCasePayload {
    pub name: String,
    pub status: String,
    pub details: Option<String>,
}

#[derive(Deserialize, Object)]
struct RecordTestsPayload {
    pub story_id: String,
    pub unit: Vec<TestCasePayload>,
    pub integration: Vec<TestCasePayload>,
}

#[derive(Deserialize, Object)]
struct AcceptanceRequest {
    pub story_id: String,
}

#[derive(Object)]
struct TestRunSummaryResponse {
    pub total: usize,
    pub passed: usize,
    pub failed: usize,
}

#[derive(Object)]
struct AcceptanceResponse {
    pub can_accept: bool,
    pub reasons: Vec<String>,
    pub warning: Option<String>,
    pub summary: TestRunSummaryResponse,
    pub missing_categories: Vec<String>,
}

#[derive(Object)]
struct ReviewStory {
    pub story_id: String,
    pub can_accept: bool,
    pub reasons: Vec<String>,
    pub warning: Option<String>,
    pub summary: TestRunSummaryResponse,
    pub missing_categories: Vec<String>,
}

#[derive(Object)]
struct ReviewListResponse {
    pub stories: Vec<ReviewStory>,
}

fn load_current_story_metadata(ctx: &AppContext) -> Result<Vec<(String, StoryMetadata)>, String> {
    let root = ctx.state.get_project_root()?;
    let current_dir = root.join(".story_kit").join("stories").join("current");

    if !current_dir.exists() {
        return Ok(Vec::new());
    }

    let mut stories = Vec::new();
    for entry in fs::read_dir(&current_dir)
        .map_err(|e| format!("Failed to read current stories directory: {e}"))?
    {
        let entry = entry.map_err(|e| format!("Failed to read current story entry: {e}"))?;
        let path = entry.path();
        if path.extension().and_then(|ext| ext.to_str()) != Some("md") {
            continue;
        }
        let story_id = path
            .file_stem()
            .and_then(|stem| stem.to_str())
            .ok_or_else(|| "Invalid story file name.".to_string())?
            .to_string();
        let contents = fs::read_to_string(&path)
            .map_err(|e| format!("Failed to read story file {}: {e}", path.display()))?;
        let metadata = parse_front_matter(&contents)
            .map_err(|e| format!("Failed to parse front matter for {story_id}: {e:?}"))?;
        stories.push((story_id, metadata));
    }

    Ok(stories)
}

fn to_review_story(story_id: &str, results: &StoryTestResults) -> ReviewStory {
    let decision = evaluate_acceptance(results);
    let summary = summarize_results(results);

    let mut missing_categories = Vec::new();
    let mut reasons = decision.reasons;

    if results.unit.is_empty() {
        missing_categories.push("unit".to_string());
        reasons.push("Missing unit test results.".to_string());
    }
    if results.integration.is_empty() {
        missing_categories.push("integration".to_string());
        reasons.push("Missing integration test results.".to_string());
    }

    let can_accept = decision.can_accept && missing_categories.is_empty();

    ReviewStory {
        story_id: story_id.to_string(),
        can_accept,
        reasons,
        warning: decision.warning,
        summary: TestRunSummaryResponse {
            total: summary.total,
            passed: summary.passed,
            failed: summary.failed,
        },
        missing_categories,
    }
}

pub struct WorkflowApi {
    pub ctx: Arc<AppContext>,
}

#[OpenApi(tag = "WorkflowTags::Workflow")]
impl WorkflowApi {
    /// Record test results for a story (unit + integration).
    #[oai(path = "/workflow/tests/record", method = "post")]
    async fn record_tests(&self, payload: Json<RecordTestsPayload>) -> OpenApiResult<Json<bool>> {
        let unit = payload
            .0
            .unit
            .into_iter()
            .map(to_test_case)
            .collect::<Result<Vec<_>, String>>()
            .map_err(bad_request)?;
        let integration = payload
            .0
            .integration
            .into_iter()
            .map(to_test_case)
            .collect::<Result<Vec<_>, String>>()
            .map_err(bad_request)?;

        let mut workflow = self
            .ctx
            .workflow
            .lock()
            .map_err(|e| bad_request(e.to_string()))?;
        workflow
            .record_test_results_validated(payload.0.story_id, unit, integration)
            .map_err(bad_request)?;

        Ok(Json(true))
    }

    /// Evaluate acceptance readiness for a story.
    #[oai(path = "/workflow/acceptance", method = "post")]
    async fn acceptance(
        &self,
        payload: Json<AcceptanceRequest>,
    ) -> OpenApiResult<Json<AcceptanceResponse>> {
        let results = {
            let workflow = self
                .ctx
                .workflow
                .lock()
                .map_err(|e| bad_request(e.to_string()))?;
            workflow
                .results
                .get(&payload.0.story_id)
                .cloned()
                .unwrap_or_default()
        };

        let decision = evaluate_acceptance(&results);
        let summary = summarize_results(&results);

        let mut missing_categories = Vec::new();
        let mut reasons = decision.reasons;

        if results.unit.is_empty() {
            missing_categories.push("unit".to_string());
            reasons.push("Missing unit test results.".to_string());
        }
        if results.integration.is_empty() {
            missing_categories.push("integration".to_string());
            reasons.push("Missing integration test results.".to_string());
        }

        let can_accept = decision.can_accept && missing_categories.is_empty();

        Ok(Json(AcceptanceResponse {
            can_accept,
            reasons,
            warning: decision.warning,
            summary: TestRunSummaryResponse {
                total: summary.total,
                passed: summary.passed,
                failed: summary.failed,
            },
            missing_categories,
        }))
    }

    /// List stories that are ready for human review.
    #[oai(path = "/workflow/review", method = "get")]
    async fn review_queue(&self) -> OpenApiResult<Json<ReviewListResponse>> {
        let stories = {
            let workflow = self
                .ctx
                .workflow
                .lock()
                .map_err(|e| bad_request(e.to_string()))?;
            workflow
                .results
                .iter()
                .map(|(story_id, results)| to_review_story(story_id, results))
                .filter(|story| story.can_accept)
                .collect::<Vec<_>>()
        };

        Ok(Json(ReviewListResponse { stories }))
    }

    /// List stories in the review queue, including blocked items and current stories.
    #[oai(path = "/workflow/review/all", method = "get")]
    async fn review_queue_all(&self) -> OpenApiResult<Json<ReviewListResponse>> {
        let current_stories =
            load_current_story_metadata(self.ctx.as_ref()).map_err(bad_request)?;
        let stories = {
            let mut workflow = self
                .ctx
                .workflow
                .lock()
                .map_err(|e| bad_request(e.to_string()))?;

            if !current_stories.is_empty() {
                workflow.load_story_metadata(current_stories);
            }

            let mut story_ids = BTreeSet::new();

            for story_id in workflow.results.keys() {
                story_ids.insert(story_id.clone());
            }
            for story_id in workflow.stories.keys() {
                story_ids.insert(story_id.clone());
            }

            story_ids
                .into_iter()
                .map(|story_id| {
                    let results = workflow.results.get(&story_id).cloned().unwrap_or_default();
                    to_review_story(&story_id, &results)
                })
                .collect::<Vec<_>>()
        };

        Ok(Json(ReviewListResponse { stories }))
    }

    /// Ensure a story can be accepted; returns an error when gates fail.
    #[oai(path = "/workflow/acceptance/ensure", method = "post")]
    async fn ensure_acceptance(
        &self,
        payload: Json<AcceptanceRequest>,
    ) -> OpenApiResult<Json<bool>> {
        let response = self.acceptance(payload).await?.0;
        if response.can_accept {
            return Ok(Json(true));
        }

        let mut parts = Vec::new();
        if !response.reasons.is_empty() {
            parts.push(response.reasons.join("; "));
        }
        if let Some(warning) = response.warning {
            parts.push(warning);
        }

        let message = if parts.is_empty() {
            "Acceptance is blocked.".to_string()
        } else {
            format!("Acceptance is blocked: {}", parts.join("; "))
        };

        Err(bad_request(message))
    }
}

fn to_test_case(input: TestCasePayload) -> Result<TestCaseResult, String> {
    let status = parse_test_status(&input.status)?;
    Ok(TestCaseResult {
        name: input.name,
        status,
        details: input.details,
    })
}

fn parse_test_status(value: &str) -> Result<TestStatus, String> {
    match value {
        "pass" => Ok(TestStatus::Pass),
        "fail" => Ok(TestStatus::Fail),
        other => Err(format!(
            "Invalid test status '{other}'. Use 'pass' or 'fail'."
        )),
    }
}