use std::collections::HashMap;
use std::path::Path;

use regex::Regex;
use toml::{self, Value};

use crate::definition::TemplateDefinition;
use crate::errors::{new_error, ErrorKind, Result};
use crate::utils::read_file;

/// Validate that the struct doesn't have bad data in it
/// and that it doesn't have obvious logic flaws
pub fn validate_definition(def: &TemplateDefinition) -> Vec<String> {
    let mut errs = vec![];
    let mut types = HashMap::new();

    for var in &def.variables {
        let type_str = var.default.type_str();
        types.insert(var.name.to_string(), type_str);

        match var.default {
            Value::String(_) | Value::Integer(_) | Value::Boolean(_) => (),
            _ => {
                errs.push(format!(
                    "Variable `{}` has a default of type {}, which isn't allowed",
                    var.name, type_str
                ));
            }
        }

        if let Some(ref choices) = var.choices {
            let mut choice_found = false;
            for c in choices {
                if *c == var.default {
                    choice_found = true;
                }
            }
            if !choice_found {
                errs.push(format!(
                    "Variable `{}` has `{}` as default, which isn't in the choices",
                    var.name, var.default
                ));
            }
        }

        // Since variables are ordered, we can detect whether the only_if is referring
        // to an unknown variable or a variable of the wrong type
        if let Some(ref cond) = var.only_if {
            if let Some(ref t) = types.get(&cond.name) {
                if **t != cond.value.type_str() {
                    errs.push(format!(
                        "Variable `{}` depends on `{}={}`, but the type of `{}` is {}",
                        var.name, cond.name, cond.value, cond.name, t
                    ));
                }
            } else {
                errs.push(format!(
                    "Variable `{}` depends on `{}`, which wasn't asked",
                    var.name, cond.name
                ));
            }
        }

        if let Some(ref pattern) = var.validation {
            if !var.default.is_str() {
                errs.push(format!(
                    "Variable `{}` has a validation regex but is not a string",
                    var.name
                ));
                continue;
            }

            match Regex::new(pattern) {
                Ok(re) => {
                    if !re.is_match(&var.default.as_str().unwrap()) {
                        errs.push(format!(
                            "Variable `{}` has a default that doesn't pass its validation regex",
                            var.name
                        ));
                    }
                }
                Err(_) => {
                    errs.push(format!(
                        "Variable `{}` has an invalid validation regex: {}",
                        var.name, pattern
                    ));
                }
            }
        }
    }

    errs
}

/// Takes a path to a `template.toml` file and validates it
pub fn validate_file<T: AsRef<Path>>(path: T) -> Result<Vec<String>> {
    let definition: TemplateDefinition = toml::from_str(&read_file(path.as_ref())?)
        .map_err(|err| new_error(ErrorKind::Toml { err }))?;

    Ok(validate_definition(&definition))
}

#[cfg(test)]
mod tests {
    use toml;

    use super::*;

    #[test]
    fn valid_definition_has_no_errors() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project_name"
            default = "My project"
            prompt = "What's the name of your project?"

            [[variables]]
            name = "database"
            default = "postgres"
            prompt = "Which database to use?"
            choices = ["postgres", "mysql"]

            [[variables]]
            name = "pg_version"
            prompt = "Which version of Postgres?"
            default = "10.4"
            choices = ["10.4", "9.3"]
            only_if = { name = "database", value = "postgres" }

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(errs.is_empty());
    }

    #[test]
    fn errors_default_not_in_choice() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project_name"
            default = "My project"
            prompt = "What's the name of your project?"

            [[variables]]
            name = "database"
            default = "postgres"
            prompt = "Which database to use?"
            choices = ["postgres", "mysql"]

            [[variables]]
            name = "pg_version"
            prompt = "Which version of Postgres?"
            default = "10.5"
            choices = ["10.4", "9.3"]
            only_if = { name = "database", value = "postgres" }

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(!errs.is_empty());
        assert_eq!(
            errs[0],
            "Variable `pg_version` has `\"10.5\"` as default, which isn\'t in the choices"
        );
    }

    #[test]
    fn errors_only_if_unkwnon_variable_name() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project_name"
            default = "My project"
            prompt = "What's the name of your project?"

            [[variables]]
            name = "pg_version"
            prompt = "Which version of Postgres?"
            default = "10.4"
            choices = ["10.4", "9.3"]
            only_if = { name = "database", value = true }

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(!errs.is_empty());
        assert_eq!(errs[0], "Variable `pg_version` depends on `database`, which wasn\'t asked");
    }

    #[test]
    fn errors_only_if_not_matching_type() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project_name"
            default = "My project"
            prompt = "What's the name of your project?"

            [[variables]]
            name = "database"
            default = "postgres"
            prompt = "Which database to use?"
            choices = ["postgres", "mysql"]

            [[variables]]
            name = "pg_version"
            prompt = "Which version of Postgres?"
            default = "10.4"
            choices = ["10.4", "9.3"]
            only_if = { name = "database", value = true }

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(!errs.is_empty());
        assert_eq!(errs[0], "Variable `pg_version` depends on `database=true`, but the type of `database` is string");
    }

    #[test]
    fn errors_validation_regex_on_wrong_type() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project"
            default = true
            prompt = "What's the name of your project?"
            validation = "[0-9]+"

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(!errs.is_empty());
        assert_eq!(errs[0], "Variable `project` has a validation regex but is not a string");
    }

    #[test]
    fn errors_invalid_validation_regex() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project_name"
            default = "My project"
            prompt = "What's the name of your project?"
            validation = "**[0-9]++"

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(!errs.is_empty());
        assert_eq!(errs[0], "Variable `project_name` has an invalid validation regex: **[0-9]++");
    }

    #[test]
    fn errors_default_doesnt_match_validation_regex() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project_name"
            default = "123"
            prompt = "What's the name of your project?"
            validation = "^([a-zA-Z][a-zA-Z0-9_-]+)$"

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(!errs.is_empty());
        assert_eq!(
            errs[0],
            "Variable `project_name` has a default that doesn\'t pass its validation regex"
        );
    }

    #[test]
    fn errors_on_unsupported_type() {
        let def: TemplateDefinition = toml::from_str(
            r#"
            name = "Test template"
            description = "A description"
            kickstart_version = 1

            [[variables]]
            name = "project_name"
            default = 1.2
            prompt = "What's the name of your project?"
            validation = "^([a-zA-Z][a-zA-Z0-9_-]+)$"

        "#,
        )
        .unwrap();
        let errs = validate_definition(&def);
        assert!(!errs.is_empty());
        assert_eq!(
            errs[0],
            "Variable `project_name` has a default of type float, which isn\'t allowed"
        );
    }
}